Apparatus for obtaining high vacua



May 4 1926.

Y 1,583,473 P. E. KLoPsTEG |=:1r m.

APPARATUS FOR OBTAINING HIGH VACUA FiledvAprl 28, 1923 2 Sheets-Sheet 1 May 4 1926. Y 1,583,473

I P. E. KLPSTEG El' Al.l

APPARATUS Fon OBTAINING HIGH vAcUA Filed Apr-i1 28, 1923 2 Sheets-Sheet 2 Patented May 4, 1926.

UNITED STATES Alaan-EIQT OFFICE.

PAULE. KLOPSTEG AND LESTER B. MANN, F CHICAGO, ILLINOIS, ASSIGNOBS T0 CENTRAL lSCIENTIFIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION Ol ILLINOIS.

APPARATUS FOR OBTAINING HIGH VACUA.

Application led April 28, 192'3. Serial No. 635,380.

To all whom 'it may concern.'

Be it known that we, PAUL E. KLoPs'rEe and LESTER B. MANN, citizens of the United States, and residents of Chicago, -county of Cook, and State of Illinois, have invented certain new and useful Improvements in Apparatus for Obtaining High Vacua, of which the following is a speciiication and which are illustrated in the accompanying drawings, forming a part thereof.

This invention relates to high vacuum pumps of the vapor type. One of the-char ac'teristics of pumps of this type heretofore patented is high resistance in the passage or conduit leading from the source of vapor to the'condenser, which has impaired the operation of the pump and increased the amount of heat required. lThe defect has generally been produced either by constriction or elongation of that passage or conduit, or by both constriction and elongation of that passage or conduit. One object of the invention is to eliminate this resistance and permit the vapor to be vgiven a correspondingly high velocity between the source and the condenser. l

Another characteristic of some pumps of this type heretofore patented has been the flow of condensed mercury, o r other liquid through a portion of the passage or conduit for the as to be exhausted. And it is another ob]ect of the invention to cause practically all the condensed liquid to return to the source of vapor through the conduit by which the vapor travels from the source.

Further objects and advantages of the invention will become, apparent as the disclosure proceeds and the description is read in connection with the accompanying drawing illustrating selectedembodiments of the invention, and in which-- Figs.-1 and 2 are longitudinal section and side elevation'respectively of one form of pump made according to the invention;

Figs. 3 and 4 are sectional views taken on the lines 3--3 and 4-4 respectively of Fig. 1;

Figs. 5 and 6are views similar to Figs. 1 and 2, illustrating another yform of pump 5 embodying the invention;

Fig. 7 is a sectional view taken on the line 7-7 of Fig. 5;

Figs. 8 and 9 are views similar Vto Figs. 1y

and 2, illustrating a further modified form of pump made according to the invention,

and

Fig. 10 is a transverse sectional view taken to form a passage or conduit 13 discharging into a collecting chamber 14. It is not4 necessary that the conduit 13 have a cross sectional area equal to that of the boiler, but it is desirable and advantageous to have the conduit comparatively large and also ,quite short, for by this means vapor produced viny the boiler passes to the collecting chamber 14 with a minimum of loss of speed and energy due to frictional resistance against the walls of the conduit', Consequently, the jet of vapor may be given such high'speed that lateral motion of molecules of vapor becomes immaterial and this speed can be producedrwith a comparatively small amount of heat applied to the boiler.

For convenience in construction .the walls 15 of the collecting chamber may be extended downwardly at 16 to surround the wall 12 of the conduit 13 and enclose an annular'l space 17, forming with the'piping 18 a passage or conduitleading from the.

vessel to be exhausted. 1

The collecting chamber 14 is provided preferablyv at its upper portion with piping 19, leading to a supporting pump. A water jacket 20 may be placed about the collecting chamber and supplied with inlet and outlet piping 21 and 22, though other cooling meansmay be used if preferred.

1n the operation of the pump the vapor condenses in the collecting chamber and deboiler to the collecting chamber, 'but preferabl the upper end of the` conduit 13 is Hare as indicated at 24, to extend slightly beneath the shoulder or constriction. This leaves the annular space 17 in open communication with the collecting chamber through an annular slit which is protected from the descending liquid on its return to the boiler. It will be advantageous if the wall 12 of the conduit 13 is reversely curved, as indicated in Fig. 1, 'for in this waythe conduit may be given a flaring mouth at the same time the passage for the gas to be exhausted will not embody any sharp corners or thelike, that would interfere with the diffusion of that gas.

However, a small amount of liquid will -lcollect in the space 17 and since conduit 13 is short the lower portion of the space 17 will ordinarily be at a high temperature.

'It is, therefore, desirable to prevent vapor generated in this space from passing up the piping 18. By making the bottom portion 26 of the wall 16 inclined, as indicated in Fig. 1, liquid in the' space 17 is made to run to the oppositeside of the conduit from the piping 18 and consequently the bulk of any vapor generated will not reach that piping. Liquid thus collected passes through a pin hole 27 back` into the boiler. This pin hole can be conveniently made by drilling through'the wall 16,`as well as' the pall 12,.then plugging the hole in the wall The relationship between the generation of vapor and the size of the collecting chamber,'with the eiciency of the cooling, limits the speed of the pump;l for if vapor is generated more rapidly than it can be collected and condensed there will be back pressure which will interfere with the diffusion of the gas into the jet. The proportions illustrated in the drawing give very efficient results, but greater speed can be had by enlarging the collecting chamber, which may done by increasing the diameter or lthe length, or both. The form of pump shown on Sheet 1 (Flgs. 1, 2, 3 and 4) lends itself very readily to manufacture from metal, such as steel, and from non-metal, such as glass. All the y parts can be made from standard tubing and the joints can be conveniently made by welding or fusing. In making the pump of steel the wall sections 26, 28 and 29 may be formed by laying a ring between the telescoping walls and fusing the ring to both walls.

In the pump shown in Figs. 5, 6 and 7, the boiler 30, conduit 31, collecting chamber 32, constriction 33, water jacket 34 and flar- 1ng mouth 35 are substantially the same as the corresponding parts shown on Sheet 1. The chief diierence between the pumps is in the conduit leading from thevessel to be exhausted. As shown in Fig/s. 5, 6 and 7,

thisk conduit encloses the collecting chamber and takes the form of a housing 36, which 'is reduced to convenient size piping at 37,

leading to the vessel .to be exhausted. The lower portion of the-housing 36 is provided with an integral flange 38 which is joined to the wall 39 corresponding to the wal1j16 in Fi 1. Above this joint the wall 39 is provi ed with a plurality of slots 40 which may beseparatedvby offset portions 41 and in this way free communication is had be- I but ithas the advantage of permitting the v vessel to be exhausted to be conveniently supported directly above the pump.

In Figs. 8, 9 and 10 a modified construe'- tion is shown which, though easily made of steel, lends itself particularly to manufacture from glass. In .this construction the boiler 46 and the conduit 47 ,are composed of 'one piece, similar in form to a test tube. The walls of the collecting chamber 48 are tubular and extend down around the co'n-y duit 47 to which they are secured by fusion or the like at 49, somewhat below the end of the piping 50, which leads to the vessel to be exhausted. The collecting chamber is reduced at 5'1 and extended in tubing 52 leading to the supporting pump. The wall of the water jacket 53 telescopes with the wall 48 of the collecting chamber and is secured thereto at 54 and is closed by a plug, or cork, or the like at 55. The construction 56 and the flaring mouth 57 are similar to those described in the other forms of pump.

As illustrated the boiler 46and conduit 47 converge slightly towards the top, but this is not suflicient to materially reduce the efficiency of the pump, especially so when the length of the conduit 47 is kept small.

In all forms of the pump the water jacket or other cooling means does not extend down to the constriction or shoulder from which the condensed liquid leaps -into the vapor conduit.

This permits that portion of the walls 15 to become and remain heated, which results in two advantages in the operation of the pump. When the descending liquid comes in contact with the heated shoulder a slight amount of vapor is formed between the liquid and the wall, that acts as a lubri- ,cant promoting the leaping of the liquid from the shoulder, 'and molecules of vapor impinging against the underside of the shoulder are prevented from collecting and running down into the annular space 17.

We claim as our invention:

1. In a high vacuum pump of the vapor type, a boiler, a collecting chamber above the boiler and provided with cooling means, a conduit between the boiler and collecting chamber and an inwardly extending projection above the upper end of the conduit and lying in the path of liquid descending from the collecting chamber.

2. In a. high vacuum pump of the vapor type, a boiler, a collecting chamber above the boiler and provided with cooling means, aconduit leading from the boiler to the collecting chamber, a second conduit vleading from the vessel to be exhausted to the collecting chamber at the same point as the first conduit and means for causing scending from the collecting chamber to pass down the first conduit.

3. In a high vacuum pump of the vaporv type, a boiler, a collecting chamber above the boiler and provided with cooling means, a conduit leading from the boiler to the collecting chamber, a second conduit leading from the vessel to be .exhausted to the collecting chamber at the same point as the first conduit, and a shoulder adjacent to the bottom of the collecting chamber overhanging the outlet to the second conduit.

liquid del 4. In a high vacuum pump of the vapor type, a boiler, a collecting chamber above the boiler, a conduit connecting the boiler with the chamber, a second conduit connected with the vessel to be exhausted and terminated lin an annular slit surrounding the -lirst conduit and a constriction overhanging the annular slit and lying in the ath of liquid assing from the collecting c 'amber to the Boiler.

5. In a high vacuum -pump of the vapor type, a boiler, a collecting chamber above the boiler, a conduit connecting the-boiler with the chamber, a second conduit connected with the vessel to be exhausted, and including an annular passage surrounding the first conduit and havin an inclined bottom in communication wit the boiler.

6. In a high vacuum pump of the vapor type, a boiler having its walls extended upwardly to form a conduit, a collecting chamber above the conduit having walls telescoping with the wall of the conduit and secured thereto, a constriction in the wall of the lcollecting chamber above the end of the conduit and tubing connected with the outer of the telescoping Walls and adapted to be 1n commumcatlon with the vessel to be exhausted.

y PAUL E. KLOPSTEG. LESTER B. MANN. 

